Electric heater



C. C. ABBOTT.

ELECTRIC HEATER.

APPLICATION FILED APR. 16, 1919.

1,345,730, Patented July 6, 1920.

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Inventor; Cha Ies C.Abbott.,

by I M His Attorney.

UNITED STATES PATENT OFFICE.

CHARLES C. ABBOTT, OF PITTSFIELD, MASSACHUSETTS, ASSIQNOR TO GENESBIAL- ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

ELECTRIC HEATER,

Application filed April 16, 1919. Serial No. 290,476.

To all whom it may concern:

Be it known that I, CHARLES C; Anno'i'r, a citizen of the United States, residing at Pittsfield, in the county of Berkshire, State of Massachusetts, have invented certain new and useful Improvements in Electric Heaters, of which the following is a specification.

My invention relates to electric heating devices and has for its obiect the provision of an improved device of this character, and which is exceedingly compact and rugged in construction, and reliable and efficient in operation. I

My invention relates more specifically to electric heating devices of the type commonly referred to as electric stoves or hot plates adapted for the heating of articles by direct contact with the flat heating surface thereof. Such devices are commonly used on electric ranges to constitute a heat ing' surface, there being ordinarily several such heating devices on a range. It is, of course, desirable to have the article to be heated in as close a thermal relation as possible with the heating element, while at the same time making the parts safe, rugged and easily renewable.

In carrying out my invention I utilize as a heating element what is commonly known as sheathed wire, that is, wire consisting of an outer sheath or casing and inclosing ,a resistance conductor surrounded by closely compact insulating material. For my present purpose I prefer to employ sheath wire of the type described in my application, Serial No. 262,722, filed November 15, 1918, in which the resistance conductor is in the form of a spiral. This form of sheath wire is well adapted for my purpose because it is inherently larger in section, and hence stiffer than sheathed wire with a straight core. Moreover, by reason of the spiral arrangement of the core wire, it is possible to get a suiiicient length of resistance conductor into a relatively small length of sheathed wire. In carrying out my invention, I form the sheathed wire into a gridwhich actually supports the article to be heated. In the case of a hot plate or stove, for instance, the sheathed wire is formed into a grid which is supported in a frame so as to be above the surface of the frame whereby the article to be heated will rest upon the grid. The article to be heated is thus in close thermal relation with the heating element, and the arrangement is very compact and simple.

In the accompanying drawings illustratmg my invention, Figure 1 is a perspective view of an electric stove or hot plate embodying my invention; Fig. 2 is a sectional view of the same.

Referring to the drawings, 10 represents an annular casing which, as shown, is of metal bent or pressed to the desired form. This casinghas a substantially flat annular ring surface 11, and a depression at the center formed by the cylindrical portion 12. Into this opening or depression the heating unit is inserted. This heating unit consists of a grid 13 formed of sheathed wire arranged in a spiral. This sheathed wire is preferably made in accordance with my previous application above referred to, and consists of a spiral resistance conductor 14 embedded in insulating material 15 and surrounded by a metal sheath 16. The material of this sheath should be such as to withstand prolonged heating at a high temperature without deterioration since the unit will preferably be run at a glowing heat. The insulating material is closely compacted by the rolling or drawing down of the sheath, all of which is explained in my said patent application. As shown, the grid is formed of two separate spirals 17 and 18 for the purpose of obtaining different degrees of heat as will be well understood. This grid 13 is mounted in supporting arms 19 which in turn are supported upon the casing at 20. It will be noted that the surface of the grid is somewhat above the flat surface 11 of the casing so that when an article as, for instance, a cooking utensil is placed upon the stove, it will rest directly upon the grid. Since the grid is operated at a glowing heat the utensil is heated both by conduction and direct radiation of heat. The terminals of the sheathed wire are brought down to a plate 21 which forms the bottom of the depressed portion. This plate merely rests upon a flange of the depressed portion so as to be removable with the heating unit and sup orting arms. The terminals are inclosed by a cover 22 held in place by lugs 23. As shown, there are three terminals so Patented. July 6,1920.

that the two parts of the grid may be connected either in series or in parallel asdesired to give different degrees of heat. A reflector 2-1 made in halves so as to be easily removable is likewise provided.

While I have described my invention as embodied in concrete form and as operating in a specific manner in accordance with the provisions of the patent statutes, it should be understood that I do not limit my invention thereto, as various modifications thereof will suggest themselves to those skilled in the art without departing from the spirit of my invention, the scope of which is set forth in the annexed claims.

'What I claim as new and desireto secure by Letters Patent of the United States, is

1. An electric heater comprising a supporting frame and a heating element consisting of a resistance conductor and an inclosing metallic tube insulated therefrom formed into a grid and mounted in said frame and extending above it so as to support articles to be heated directly thereon.

2. An electric heater comprising a supporting frame having a substantially flat upper surface and a heating element consisting of a resistance conductor and an inclosing metallic tube insulated therefrom formed into a grid and mounted in said frame so as to the frame.

3. An electric heater comprising a casing project above the surface of having a substantially fiat upper surface 'and a depressed central portion, a heating unit consisting of a resistance conductor and an inclosing metallic tube insulated therefrom formed into a grid and mounted in said depression and terminals for said heating unit in the bottom of the depressed portion.

5. An electric heater comprising a casing having a substantially fiat upper surface and a heating unit consisting of a resistance conductor and an inclosing metallic tube insulated therefrom formed into a grid and detachably mounted within said casing so as to present a fiat surface which projects above the surface of the casing.

In witness whereof, I have hereunto set my hand this 14th day of April, 1919.

CHARLES C. ABBOTT. 

